I. Field of the Invention
The present invention relates to an improved soil aeration device.
II. Description of Prior Art
In grass fields and other lawn areas which experience sustained vehicular and pedestrian traffic, the turf surface and underlying soil can become undesirably compacted. The problems associated with soil compaction are that rain and fertilizing chemicals are prevented from fully penetrating the ground. The short-term effect of such a condition is that the field will remain soggy for longer periods after a rain, and the long-term effect is the prevention of deep and healthy root system and proper grass growth. Turf aeration is the process of creating channels in the soil so that water, air, and fertilizers can penetrate the ground and be dispersed effectively throughout the soil.
Many devices have been developed to alleviate soil-compaction problems ranging from pitchforks to heavy, tractor-pulled machinery having multiple, reciprocating tines. One tractor pulled heavy commercial device common in the industry today is the turf aerator manufactured by Verti-Drain® under U.S. Pat. No. 4,422,510 issued to de Ridder (hereinafter “de Ridder”), hereby incorporated by reference. That device teaches a main frame which supports several rotary shafts, drive links, and connecting rods which reciprocate a number of pantograph-type mechanisms. In each mechanism, a tine holder having soil-piercing tines is pivotally attached to an upper link in the mechanism, and a lower link supports a spring device which allows the tines to rotate within the soil to create a drain channel. The device is typically powered by the power take-off (PTO) drive of the pulling tractor. The chief advantage claimed by that reference is that the turf surface remains largely undisturbed because of the manner in which the path of the tines is substantially vertical during penetration and withdrawal due to the action of the pantograph mechanism. Examples of Verti-Drains are shown in FIGS. 1-5.
Another device common in the industry is the “Soil Reliever”, manufactured by Southern Green, Inc. and described in U.S. Pat. Nos. 5,709,272 and 5,570,746, both incorporated by reference in their entirety. The Soil Reliever is a tractor pulled device, PTO powered, and also has a main frame supporting a rotary shaft which drives upper links. Associated with each upper link is a lower link pivotally attached to the frame. The upper link connects to the lower link to cause the lower link to reciprocate. Pivotally attached to the distal end of the lower link is a tine holder, containing a number of removable times. Attached between the tine holder 30 and the frame, below the lower link, is a spring member for biasing the spring against a stop positioned on the lower link. Examples of the Soil Reliever are shown in FIGS. 6-7.
The main frames of both the Verti-Drain device and the Soil Reliever device contains a rotatable “front” roller (shown in FIGS. 1, 5 and 7 as reference 10) attached to the main frame 6 (for reference purposes, the “front” of the aeration devise is the PTO end, that is, the end closest to the tractor). Front roller 10 is generally placed forward of the plane of the main frame, and hence, may be attached to the main frame with wings 15 as shown in FIGS. 5 and 7. Front roller 10 may be vertically adjustable as shown in FIGS. 5 and 7. Several Verti-Drain models also have a rear roller (shown as 12 in FIGS. 2, 3 and 4) positioned rearward of the plane of the main frame 6 and behind the tine heads 30. On these Verti-Drain devices, the rear roller 12 rotates in a frame 13, and the frame 13 is generally pivotally connected to the main frame 6 of the device (See FIG. 3).
Both the Verti-Drain and the Soil Reliever's main frame is connected to the tractor through a three point pick up harness on the device, generally consisting of two lower attachment points 100 rigidly connected to the main frame 6 and a top attachment point 101 also rigidly connected to the main frame 6. See generally, FIGS. 1, 5 and 8. Powered adjustment arm 200 can be powered by the PTO, hydraulics or other means, and can include an intermediate arm positioned between the tractor powered adjustment arm and top attachment point (see FIGS. 8 and 12).
Lower attachment points connect pivotally to arms on the tractor, and top attachment point 101 also pivotally connects directly or indirectly to a powered adjustment arm 200 on the tractor. The top attachment point 101 of the three point harness, as shown in FIGS. 1, 5 and 7, consists of two splayed arms 101a and a top rail 101b. The two splayed arms 101 fixedly connect at one end to the lower main frame, and at the other end to the top rail 101b. Top rail 101b is rigidly attached between the top of the main frame 6 and the two splayed arms. Additionally stiffening of the top rail 101a can be provided as shown in FIG. 12. The splayed arms 101a diverge from the top attachment point 101 to allow the PTO to attach therebetween, as shown in FIG. 5. The top attachment point 101 of the harness thus forms a rigid structure located between the bottom and top of the main frame 6, and has a coupling means 101c (as shown, a pin, but other types of couplings could be used) to couple the top attachment point 101 to the tractor's powered adjustable arm 200.
Hence, the aerator's three point harness is a rigid structure on the device but is pivotally mounted at the three connection points with the tractor or pulling vehicle. This three point harness is used in conjunction with the tractor's three point hitch system to raise and lower the aerator. When lowered or deployed, the aerator's front roller contacts the ground allowing the working end (the tines) to be placed in operational contact with the ground (shown in FIG. 6A). When lifted, the entire aerator is lifted off the ground (as shown in FIG. 6B) to allow for ease transportation of the aeration between working sites or locations.
The position of the working end of the device (the tine heads) with respect to the ground is set by adjusting the length of the pulling vehicles powered adjustment arm (or intermediary member) 200. As this arm is shortened, the coupling point 101c of the top rail 101b to the powered adjustment arm 200 is drawn closer to the tractor, thereby raising the tine heads upwardly. As this powered adjustment arm 200 is lengthened, the coupling point 101c of the top rail 101b to the powered adjustment arm 200 is pushed further from the tractor, lowering the tine heads downwardly. If the tine head is not properly positioned with respect to the ground, entry angle and depth of penetration will be improper, as shown in FIG. 18. Hence, to keep the times in proper position with respect to the ground when covering complex terrain; the tractor operator must constantly monitor and adjust the length of the top adjustment bar.